(B) Allocation. The costs for covered services must be allocated among the participants based on their respective shares of the reasonably anticipated benefits from those services, without regard to whether the anticipated benefits are in fact realized. Reasonably anticipated benefits are benefits as defined in paragraph (l)(3)(i) of this section. The allocation of costs must provide the most reliable measure of the participants' respective shares of the reasonably anticipated benefits under the principles of the best method rule. See 1.482-1(c). The allocation must be applied on a consistent basis for all participants and services. The allocation to each participant in each taxable year must reasonably reflect that participant's respective share of reasonably anticipated benefits for such taxable year. If the taxpayer reasonably concluded that the shared services arrangement (including any aggregation pursuant to paragraph (b)(7)(iii)(B) of this section) allocated costs for covered services on a basis that most reliably reflects the participants' respective shares of the reasonably anticipated benefits attributable to such services, as provided for in this paragraph (b)(7), then the Commissioner may not adjust such allocation basis.